1. Field of the Invention
The present invention generally relates to information processing and, more particularly, to an information processing apparatus, and a power supply control method for an information processing apparatus.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 10-255451 discusses a power supply control method for a mirroring system, in which a system is protected by simultaneously writing data into a plurality of hard disk drives (HDDs). Further, Japanese Patent Application Laid-Open No. 10-255451 discusses that, after writing into the HDDs is completed, a power of the HDDs is turned off.
Further, the functions of a mirroring control unit of such a type inserted as an addition of option between a system control central processing unit (CPU) and the HDDs include (1) a mirror function (1), a rebuild function (2), and a patrol function (3) as described below.
The mirror function (1) corresponds to a function for executing simultaneous writing on all HDDs connected, in response to a write command from a host. The rebuild function (2) corresponds to a function for copying onto an HDD from a copying source HDD to a copying destination, when an HDD has failed. The patrol function (3) corresponds to a function for executing a reading test of the HDDs connected for all regions at a predetermined timing, during a normal service.
As described above, there are available three functions in which the mirroring system can be implemented, i.e., the mirror function (1), the rebuild function (2), and the patrol function (3). In particular, for the rebuild and patrol functions (2) and (3), processing can be executed even when the system control CPU does not operate.
However, conventionally, even in such a case, power is supplied to the system control CPU. In the conventional configuration, the above-described rebuild and/or patrol functions (2) or (3) is required, even though their operation(s) are enabled by supplied power of several watts only to the mirroring control circuit and the HDDs, to supply power consumption of several tens of watts to the system control CPU for several tens of minutes to several hours.
If a configuration to suspend the rebuild or the patrol when entering into a sleep mode is employed, power-saving can be implemented. However, in such a configuration, in an apparatus with a setting of frequently entering into the sleep mode, a significant number of days may be required to secure energization for a length of accumulative time required until operation of the rebuild or the patrol is completed. In this case, the system protection by the mirroring system cannot be carried out for that period of time.